[petsc-dev] strangness in Chebyshev estimate of eigenvalues

[Mark Adams]

Other than set userandom = PETSC_TRUE, should I do anything else?

I see:

ierr = VecSetRandom(B,cheb->random);CHKERRQ(ierr);

Should I use a special one or change this default to the special one?

On Tue, May 17, 2016 at 3:19 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Tue, May 17, 2016 at 2:11 PM, Jed Brown <jed at jedbrown.org> wrote:
>
>> Barry Smith <bsmith at mcs.anl.gov> writes:
>> >   Sounds like Jed is saying he is ok with making the default use the
>> >   random number generator. Do this in a branch and be aware that you
>> >   have to update a bunch of the test output files to match the new
>> >   convergence histories introduced by the change.
>>
>> Sure, but if it's all the same to you all, let's use a hash.  This guy
>> seems to have a convenient permutation of 32-bit integers.  (Overkill
>> for us, but that's not a problem.)
>>
>> http://stackoverflow.com/a/12996028/33208
>>
>> Use i=(i >> 32)^i for 64-bit input.
>>
>
> Should we just make this another Random implementation which is only for
> testing?
>
>   Matt
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
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